MXPA99010164A - Welding electrode reshaping device - Google Patents

Abstract

A welding electrode dressing device in particular in automated welding stations comprises an electrode treatment head (11, 111) equipped with upsetting members (15, 115) which reshape the tip of an electrode inserted in it without removing material. Advantageously the treatment head (11, 111) comprises two treatment seats (19, 119) arranged on opposite sides thereof to each receive the end (12) of a pair of welding gun electrodes.

Description

WELDING ELECTRODE REFORMER DEVICE DESCRIPTION OF THE INVENTION The present invention relates to a device for coating welding electrodes and in particular in automatic welding stations. It is known that the electrodes that make contact with the sheet of metal to be welded are a consumable part of a resistance welding system. For reasons of conductivity and contact resistance the electrodes should be made almost of pure copper, which is known to be a malleable ductile material. During use, the electrodes are subjected cyclically to high pressures with high temperatures and undergo a process of plastic deformation which changes its shape and affects the quality of the welding. To limit the deterioration of quality beyond acceptable limits in practice, devices called electrode cloths are used which periodically laminate the upsetting material with small lamination cutters sized to restore the original shape of the electrode tip. Since the repasadores work by means of the removal of the material, they can only intervene a small number of times. The revision operations are therefore separated in time and between one operation and the next the quality of the welding joints suffer a progressive deterioration up to the limit of affectation. However, the repasadores that remove the material considerably shorten the useful life of the electrodes resulting in an increase in operating costs. The general purpose of the present invention is to select the aforementioned disadvantages by making available a repasador device which can be used frequently with optimal results and without limiting the useful life of the electrodes. In view of this purpose, it is sought to provide in accordance with the present invention, a device for reviewing welding electrodes in particular in automated welding stations and comprising an electrode treatment head fitted with altered members which reform the tip of the electrode inserted in it without removing the material. BRIEF DESCRIPTION OF THE DRAWINGS To clarify the explanation of the innovative principles of the present invention and their advantages compared with the prior art, described below with the help of the attached drawings, possible modalities thereof by means of non-limiting examples that apply such principles. In the drawings: FIGURE 1 shows a diagrammatic side view partially in cross section along the plane of section II of FIGURE 2 of a device according to the present invention, and FIGURE 2 shows a plan view of the device of FIG. FIGURE 1, FIGURE 3 shows a cross-sectional side elevation view along the section plane III of Figure 4 of a possible variant of the device according to the present invention, FIGURE 4 shows a plan view in cross section along the cutting plane IV-IV of the FIGURE 3, and FIGURE 5 is a partial view of another variant of the device of FIGURE 3. Referring to the FIGURES, FIGURE 1 shows a reforming device indicated in its entirety by the reference number 10 comprising a treatment head 11. for reviewing electrodes 12 of a robotic welding gun. The gun is not shown or described here as it is essentially prior art. This gun can be part of an automated welding station where a plurality of robotic arms perform processing on an object such as, for example, a car body. The device 10 is supported by a support 13 appropriately arranged in the station so that the robotic arms can transport the electrodes and hold the treatment head on both sides. An electric motor 14 drives the upsetting members 15 located in the treatment head to make the upsetting of the tip of the electrode exploiting the malleability and ductility of the material forming the electrodes. The upset members have a shape that defines a upsetting seat 16, 17 for each electrode of the gun with the seat being dimensioned as desired as the tip of the electrode. As can also be seen in FIGURE 2, in the described embodiment, the upsetting members are made in the form of three satellites 15 with the periphery sized with seats 16 and 17. The satellites are accommodated with the axes of rotation 18 in the vertices of an equilateral triangle to be opposite one another opposite an opening 19 for introducing the tip of the electrode into the reformer device. The satellites 15 are supported by their own plain bearings 22 by a satellite fastener 20 having bearings 21 that support the body of the device. The satellite fastener 20 is rotated by the motor 14 by means of a transmission belt 23. During use, after a predetermined number of welding or even after a welding, the welding gun ends in the head 11 for fixing the electrodes with the tips as shown in FIGURE 1. The rotation of the satellite fastener and consequently of the satellites around the tips of the electrode perform the upsetting of the tips to reform them to their original shape. It should be noted that the flat shape of the upsetting head 11 is perfectly compatible with the normal openings of the welding gun. FIGURE 3 shows a second embodiment of a device according to the present invention. For convenience, details similar to those of the above embodiments are indicated by the same numbers increased by 100. The device of FIGURE 3 indicated in its entirety by the reference numeral 110, comprises a treatment head 111 for reviewing the electrodes 12. and is supported by a support 113. In contrast to the device 10, the device 110 is supported in an intermediate position between its ends with the motor 114 arranged in a hanging manner on the opposite side of the treatment head. The motor 114 drives a belt 123 by stressing the members 115 located on the head 111. The upsetting head 111 is essentially similar to the head 11 described above for performing the upsetting of the electrodes inserted in an opposite manner therethrough through the openings 119. Advantageously, as can be seen in Figure 3, the support for the device 110 jumps by means of spring units 130 and comprises pins 131 integrated in the body 136 of the device 110 and running in seats 135 made in a plate 132 of the support 113. On the two sides of the plate 132 the springs 133, 134 are located, each reacting between one end of the respective pin and the plate itself to provide a two-way elastic support in the direction of the pulse of the electrodes against the device. This elastic support allows the device to move properly under the impulse of the welding guns that come into contact with the two processing heads. In addition, in the upsetting head 111, the device 110 has a second processing head or cleaning head generally indicated by the reference number 125. This second head 125 comprises a tool 126 designed to perform the cleaning of the surface with a removal of material insignificant. The tool is activated by the motor 114 through a second belt 127. The tool may be, for example, in the form of an abrasive lightly coated with diamond or some other tool suitable for the purpose, for example with a cutting flange. appropriate. As you can see in FIGURE 4, the tool 126 is projected from a protective cover 128 through an opening 129 so that the pair of electrodes 12 of a gun can rest on the work surface of the tool 126. In this way, it is possible to perform the cleaning of the end of the electrode on the which is a slightly flat area (called 'lens') that remains despite the action of the reformer rollers. In this area are fixed oxides, zinc slag and the like which form an alloy with the metal of the electrodes and reduce the passage of electric current resulting in a reduction in the quality of the welding. Advantageously, the tool can be configured to maintain a slight curvature of the lens. This can be easily obtained with a tool dimensioned from a soft floating disk or brush. The transport of the disc tool can be carried out "" first for one electrode and then for the other or simultaneously for both electrodes by partial closing of the gun on the disc. In the latter case it is necessary to check the closing door of the gun to have the correct necessary pressure for the flattening, FIGURE 5 shows a variant of the flattener head indicated in its entirety with the reference number 225. In this variant, the head 225 comprises two cleaning discs 226a, 226b mounted and keyed in a sliding manner on an axis 240 rotated by belt 127. Between the two discs a spring 241 is accommodated which pushes them to separate them. The two electrodes approach the two discs from the opposite directions and each electrode rests on the working surface of one of the two discs. The support can be carried out first for one electrode and then for the other or simultaneously by partial closing of the gun. The support force of the electrode on the disc is determined by the spring 240. In this way it is easy to supply a predetermined support force even allowing the variability of the placement of the electrode tip, which also depends on the consumption of the electrode due to the welding work. Now it is clear that the present purposes have been achieved. As no material is removed, the possible number of operations on an electrode is theoretically unlimited and in each welding cycle the electrode appears practically as new with a quality assured throughout the cycle. The useful life of the electrodes is considerably prolonged with considerable savings.

Even when the cleaning head is used, the removal of the material is negligible since this head basically only removes the surface oxides and does not reform the electrode. As another advantage, by ensuring the quality of the welding tip it will be possible to reduce the amount of redundant tip normally applied to the object to be welded resulting in advantages in time and cost of production. Finally, no chips are produced that must be removed from the processing area. Naturally, the above description of the modalities applying the innovative principles of the present invention is given by non-limiting examples of the principles within the scope of the exclusive rights claimed herein. For example, the shapes and proportions of the parts of the device components may vary with specific needs.

Claims (9)

1. CLAIMS 1. A welding electrode replenishing device in particular in automated welding stations and characterized in that it comprises an electrode treatment head equipped with upsetting members which reform the tip of an electrode inserted therein without removing the material. The device according to claim 1, characterized in that the treatment head comprises two treatment seats arranged on opposite sides thereof so that each receives the end of an electrode from an electrode pair of a welding gun. The device according to claim 1, characterized in that the upsetting members comprise three satellites with a periphery dimensioned for the desired upsetting and arranged with an axis of rotation at the vertices of an equilateral triangle being supported on a satellite fastener that it is rotated by an engine with the mutually facing parts of the three satellites defining an upsetting seat for the tip of the electrode. 4. The device according to claim 1, characterized in that it comprises another treatment head with a tool for cleaning the ends of the electrodes that come into contact with each other. The device according to claim 4, characterized in that the cleaning tool comprises at least one rotating abrasive disk. The device according to claim 4, characterized in that the cleaning tool comprises two parallel discs mounted in such a way that they slide on an axis of rotation between the two discs having a pulse spring that provides a sliding support that jumps to the two discs. The device according to claim 1, characterized in that it comprises a floor support arranged in an intermediate position between the treatment engine and the head. The device according to claim 1, characterized in that it comprises a floor support with jumping support means. The device according to claim 7, characterized in that the jumping support means comprises pins constrained to the body of the device and that run the seat in the bracket being fitted on each mutually opposite driving spring pin between the ends of the pin respective and the support for supplying a two-way spring support.